The objective
of this project was to investigate the abundance of commercial
fish species as a food supply for marine mammals, particularly
Steller sea lions. Bottom trawl surveys were conducted
near three rookeries in the Gulf of Alaska. Small
demersal fishes were targeted within foraging range of
the sea lion rookeries on Akun, Atkins and Marmot Island.
The most abundant species in the total catch from all
gear types were rock sole, northern sculpin, Pacific halibut,
walleye pollock, butter sole, Aleutian alligator fish,
arrowtooth flounder, and fourhorn poacher. Catch-per-unit-effort
(CPUE) was estimated as number of fish per 10 min. tow
and was found to differ among gear types and mesh sizes.
Species composition and abundances differed significantly
among rookeries when CPUE's from the most frequently used
gear type were compared. Rock sole, mostly age-0 fish,
was the most abundant species at Akun Island, whereas
northern sculpin was most abundant at Atkins and Marmot
Islands. The observed patterns of CPUE by sampling
location indicated a decreasing trend in CPUE from west
to east for most species. Observed species composition
and abundances do not reflect all pre available to juvenile
Steller sea lions within feeding range of the rookeries
because only trawlable areas were sampled and because
the size range of fishes sampled is smaller than the average
size of prey in sea lion stomachs. Nevertheless, differences
are believed to reflect real differences in prey availability
among rookeries that potentially affect sea lion feeding.